CN110678957A

CN110678957A - Electron multiplier

Info

Publication number: CN110678957A
Application number: CN201880035055.2A
Authority: CN
Inventors: 增子太地; 浜名康全; 西村�一; 渡边宏之
Original assignee: Bangsong Photonics Co Ltd
Current assignee: Bangsong Photonics Co Ltd; Hamamatsu Photonics KK
Priority date: 2017-06-30
Filing date: 2018-04-10
Publication date: 2020-01-10
Anticipated expiration: 2038-04-10
Also published as: EP3648139A1; WO2019003566A1; CN110678957B; RU2020103415A3; EP3648139B1; US10727035B2; JP6817160B2; RU2756843C2; EP3648139A4; JP2019012657A; RU2020103415A; US20200176236A1

Abstract

The present embodiment relates to an electron multiplier having a structure for suppressing resistance value variation in a wider temperature range and stabilizing the resistance value variation. In the electron multiplier, the resistive layer sandwiched between the substrate and the secondary electron emission layer made of an insulating material is made of a single metal layer in which a plurality of metal blocks made of a metal material having a positive temperature characteristic in resistance value are two-dimensionally arranged on a layer formation surface that is aligned with or substantially parallel to the channel formation surface of the substrate in a state of being adjacent to each other with a part of the first insulating material interposed therebetween.

Description

Electron multiplier

Technical Field

The present invention relates to an electron multiplier that emits secondary electrons in response to incidence of charged particles.

Background

As an electron multiplier having an electron multiplying function, an electron multiplier having a Channel, and an electronic device such as a microchannel Plate (hereinafter, referred to as "MCP") are known. These are used in electron Multiplier tubes (electron Multiplier tubes), mass spectrometers, image intensifiers, and photomultiplier tubes (hereinafter referred to as "PMT"). Lead glass has been conventionally used as a substrate of the electron multiplier, but in recent years, there has been an increasing need for forming a film on a channel provided on a lead-free substrate, such as a secondary electron emission surface, with high accuracy, without using a lead glass for the electron multiplier.

As a technique capable of performing such precise film formation control, for example, an atomic layer Deposition (hereinafter, referred to as "ALD") method is known, and MCP (hereinafter, referred to as "ALD-MCP") manufactured by using this film formation technique is disclosed in, for example, patent document 1 below. In the MCP of patent document 1, a resistive layer capable of adjusting a resistance value formed directly below a secondary electron emission surface is formed by using an MCP having Al layers interposed therebetween by an ALD method₂O₃The insulating layer is formed with a resistance layer having a laminated structure of a plurality of CZO (zinc-doped copper oxide nano alloy) conductive layers. Patent document 2 discloses a technique for producing a resistive film having a laminated structure in which an insulating layer and a plurality of conductive layers made of W (tungsten) and Mo (molybdenum) are alternately arranged, by producing a film capable of adjusting a resistance value by ALD.

Documents of the prior art

Patent document

Patent document 1: specification of U.S. Pat. No. 8,237,129

Patent document 2: specification of U.S. Pat. No. 9,105,379

Disclosure of Invention

Technical problem to be solved by the invention

The present inventors have studied a conventional ALD-MCP for forming a secondary electron emission layer or the like by an ALD method, and as a result, have found the following technical problems. That is, although neither of the

above patent documents

1 and 2 is described, it has been found by the inventors' study that ALD-MCP using a resistance film formed by ALD method is inferior in temperature characteristics of resistance value to conventional MCP using Pb (lead) glass. In particular, the ambient temperature of the image intensifier and PMT equipped with MCP is in a wide range from low temperature to high temperature, and ALD-MCP is being developed in which the influence of the ambient temperature is small.

One of the main causes of the MCP affected by the operating environment temperature is the temperature characteristic (variation in the resistance value of the MCP) described above. Such temperature characteristics are indexes indicating how much the current (current) flowing through the MCP fluctuates depending on the outside air temperature when the MCP is used, and the more excellent the temperature characteristics of the resistance value, the smaller the fluctuation of the current flowing through the MCP when the operating environment temperature is changed, and the wider the operating temperature environment of the MCP.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an electron multiplier having a structure for suppressing and stabilizing a variation in resistance value in a wider temperature range.

Means for solving the problems

In order to solve the above-described problems, the electron multiplier according to the present embodiment is applicable to an electronic device such as a microchannel plate (MCP) and a channel multiplier, which are formed by ALD, for example, for forming a secondary electron emission layer constituting an electron multiplication channel, and includes at least a substrate, a secondary electron emission layer, and a resistive layer. The substrate has a channel-forming surface. The secondary electron emission layer is made of a first insulating material and has a bottom surface facing the channel formation surface and a secondary electron emission surface facing the bottom surface and emitting secondary electrons in response to incidence of the charged particles. The resistive layer is sandwiched between the substrate and the secondary electron emission layer. In particular, the resistive layer includes a metal layer in which a plurality of metal blocks made of a metal material having a positive temperature characteristic in resistance value are two-dimensionally arranged on a layer formation surface that is aligned with or substantially parallel to the channel formation surface in a state of being adjacent to each other with a part of the first insulating material interposed therebetween. Further, the number of metal layers present between the channel-forming surface and the secondary-electron emission surface is limited to 1.

The embodiments according to the present invention will be more fully understood from the following detailed description and the accompanying drawings. These examples are shown for the purpose of illustration only and should not be construed as limiting the scope of the invention.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. However, the detailed description and the specific examples are intended to illustrate preferred embodiments of the present invention, and are given by way of illustration only, and it is apparent that various changes and modifications within the scope of the present invention will be apparent to those skilled in the art from this detailed description.

Effects of the invention

According to the present embodiment, the resistance layer formed directly below the secondary electron emission layer is formed only by the metal layer in which the plurality of metal blocks made of the metal material having the positive temperature characteristic in the resistance value are two-dimensionally arranged on the predetermined plane in a state of being adjacent to each other with a part of the insulating material interposed therebetween, and thus the temperature characteristic of the resistance value of the electron multiplier can be effectively improved.

Drawings

Fig. 1 is a diagram showing the structure of various electronic devices to which the electron multiplier according to the present embodiment can be applied.

Fig. 2 is a diagram showing examples of various cross-sectional structures of the electron multiplier according to the present embodiment and the comparative example.

Fig. 3 is an electron conduction model showing the structure of the electron multiplier, particularly the resistive layer according to the present embodiment.

Fig. 4 is a diagram for quantitatively explaining a relationship between the temperature and the electrical conductivity of the electron multiplier, particularly the resistive layer according to the present embodiment.

Fig. 5 is a graph showing the temperature dependence of the electrical conductivity of each sample including a single Pt layer having a different film thickness as a resistive layer.

FIG. 6 is a TEM (Transmission Electron Microscope) image of a cross section of the Electron multiplier having the cross-sectional structure shown in FIG. 4 (a) and an SEM (Scanning Electron Microscope) image of the surface of the single Pt layer (resistive layer).

Fig. 7 is a diagram showing examples of various cross-sectional structures applicable to the electron multiplier according to the present embodiment.

Fig. 8 is a view showing an example of a cross-sectional structure (corresponding to the cross-section of fig. 4 (a)) of an electron multiplier according to a comparative example and a TEM image thereof.

Fig. 9 is a graph showing the temperature characteristics (during 800V operation) of the normalized resistance of each of the MCP sample to which the electron multiplier according to the present embodiment is applied and the MCP sample to which the electron multiplier according to the comparative example is applied.

FIG. 10 is a diagram obtained by XRD (X-Ray Diffraction) analysis of a measurement sample corresponding to the electron multiplier according to the present embodiment, a measurement sample corresponding to the electron multiplier according to a comparative example, and an MCP sample to which the electron multiplier according to the present embodiment is applied.

Description of the reference numerals

1 … MCP (microchannel plate), 2 … channel multiplier, 12 … channel, 100 … substrate, 101 … channel forming surface, 110 … secondary electron emission layer, 111 … secondary electron emission surface, 120 … resistive layer, 121 … Pt block (metal block), 130 … base layer, 140 … layer forming surface.

Detailed Description

[ description of embodiments of the invention of the present application ]

First, the contents of the embodiments of the present invention will be described separately.

(1) The electron multiplier according to the present embodiment is applicable to an electronic device such as a microchannel plate (MCP) and a channel multiplier, which are formed by an ALD method for forming a film such as a secondary electron emission layer constituting an electron multiplication channel, as one embodiment thereof, and includes at least a substrate, a secondary electron emission layer, and a resistive layer. The substrate has a channel-forming surface. The secondary electron emission layer is made of a first insulating material and has a bottom surface facing the channel formation surface and a secondary electron emission surface facing the bottom surface and emitting secondary electrons in response to incidence of the charged particles. The resistive layer is sandwiched between the substrate and the secondary electron emission layer. In particular, the resistive layer includes a metal layer in which a plurality of metal blocks made of a metal material having a positive temperature characteristic in resistance value are two-dimensionally arranged on a layer formation surface that is aligned with or substantially parallel to the channel formation surface in a state of being adjacent to each other with a part of the first insulating material interposed therebetween. Further, the number of metal layers present between the channel-forming surface and the secondary-electron emission surface is limited to 1.

In the present specification, the "metal block" means a metal sheet which is disposed in a state of being completely surrounded by an insulating material and shows a clear crystallinity when the secondary electron emission layer side is viewed from the layer formation surface. In this structure, the resistance layer preferably has a temperature characteristic in which the resistance value of the resistance layer at a temperature of 20 ℃, the resistance value of the resistance layer at-60 ℃ is 2.7 times or less and the resistance value of the resistance layer at +60 ℃ is 0.3 times or more. In addition, as an index indicating the crystallinity of the metal nugget, for example, in the case of a Pt nugget, peaks having a full width at half maximum of 5 ° or less appear at least on the (111) plane and the (200) plane in a pattern obtained by XRD analysis.

(2) As an embodiment of the present embodiment, the electron multiplier may further include a base layer made of a second insulating material provided between the substrate and the secondary electron emission layer. In this case, the base layer has a layer formation surface at a position facing the bottom surface of the secondary electron emission layer.

(3) As an embodiment of the present embodiment, the first insulating material and the second insulating material may be different from each other. In contrast, as an embodiment of the present embodiment, the second insulating material may be the same insulating material as the first insulating material. In addition, as an aspect of the present embodiment, the secondary electron emission layer may be set thicker than the base layer with respect to the thickness of each layer defined along the lamination direction from the channel formation surface to the secondary electron emission surface. In contrast, as an embodiment of the present embodiment, the secondary electron emission layer may be set thinner than the base layer with respect to the thickness of each layer defined along the stacking direction from the channel formation surface to the secondary electron emission surface.

(4) As an aspect of the present embodiment, it is preferable that at least 1 group of metal blocks adjacent to each other with a part of the first insulating material interposed therebetween among the plurality of metal blocks constituting the metal layer satisfy the following relationship: the minimum distance of the 1 group of metal blocks is shorter than the average thickness of the metal blocks specified in the lamination direction from the passage forming surface to the secondary electron emission surface. In the present specification, the "average thickness" of the metal block means the thickness of a flat film formed by flattening a plurality of metal blocks two-dimensionally arranged on the layer formation surface, and the thickness of the metal layer including the plurality of metal blocks is defined by the "average thickness".

As described above, the respective modes listed in the column of [ description of the embodiment of the present invention ] can be applied to each of the remaining all modes or to all combinations of the remaining modes.

[ details of embodiments of the invention of the present application ]

Specific examples of the electron multiplier according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to these examples, and is defined by the claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein. In the description of the drawings, the same components are denoted by the same reference numerals, and redundant description is omitted.

Fig. 1 is a diagram showing the structure of various electronic devices to which the electron multiplier according to the present embodiment can be applied. Specifically, (a) of fig. 1 is a partially broken view showing a representative structure of an MCP to which the electron multiplier according to the present embodiment can be applied, and (b) of fig. 1 is a cross-sectional view of a channel multiplier to which the electron multiplier according to the present embodiment can be applied.

MCP1 shown in fig. 1 (a) includes: a glass substrate having a plurality of through holes functioning as channels 12 for electron multiplication; an insulating ring 11 for protecting the side surface of the glass substrate; an input-side electrode 13A provided on one end surface of the glass substrate; and an output-side electrode 13B provided on the other end surface of the glass substrate. A predetermined voltage is applied between the input side electrode 13A and the output side electrode 13B by the voltage source 15.

Further, the channel multiplier 2 of fig. 1 (b) includes: a glass tube having a through hole functioning as the electron multiplying channel 12; an input side electrode 14 provided at an input side opening portion of the glass tube; and an output side electrode 17 provided at an output side opening portion of the glass tube. In the channel multiplier 2, a predetermined voltage is also applied between the input-side electrode 14 and the output-side electrode 17 by the voltage source 15. When the charged particles 16 enter the channel 12 from the input-side opening of the channel multiplier 2 in a state where a predetermined voltage is applied between the input-side electrode 14 and the output-side electrode 17, the discharge of secondary electrons (cascade multiplication of secondary electrons) according to the entrance of the charged particles 16 is repeated in the channel 12. Thereby, the secondary electrons cascade-multiplied in the tunnel 12 are emitted from the exit-side opening portion of the tunnel multiplier 2. This cascade multiplication of secondary electrons is also performed in each channel 12 of the MCP shown in fig. 1 (a).

Fig. 2 (a) is an enlarged view of a portion of MCP1 shown in fig. 1 (region a indicated by a dotted line). Fig. 2 (B) is a diagram showing a cross-sectional structure of the region B2 shown in fig. 2 (a), and is a diagram showing an example of a cross-sectional structure of the electron multiplier according to the present embodiment. Note that fig. 2 (c) is a view showing a cross-sectional structure of the region B2 shown in fig. 2 (a) and another example of the cross-sectional structure of the electron multiplier according to the present embodiment, similarly to fig. 2 (B). The cross-sectional structures shown in fig. 2 (B) and 2 (c) substantially match the cross-sectional structure of the region B1 of the channel multiplier 2 shown in fig. 1 (B) (however, the coordinate axes shown in fig. 1 (B) do not match the coordinate axes of fig. 2 (B) and 2 (c)).

As shown in fig. 2 (b), an example of the electron multiplier according to the present embodiment is constituted as follows: a substrate 100 made of glass or ceramic; a base layer 130 provided on the channel forming surface 101 of the substrate 100; a resistive layer 120 provided on the layer forming surface 140 of the undercoat layer 130; and a secondary electron emission layer 110 having a secondary electron emission surface 111 and disposed so as to sandwich the resistive layer 120 together with the underlayer 130. Here, the secondary electron emission layer 110 is made of Al₂O₃MgO, etc. of a first insulating material. In order to increase the gain of the electron multiplier, MgO having high secondary electron emission capability is preferably used. The base layer 130 is made of Al₂O₃、SiO₂Etc. of a second insulating material. The resistive layer 120 sandwiched between the underlayer 130 and the secondary electron emission layer 110 is a single layer composed of a plurality of metal blocks having a positive temperature characteristic in resistance value and an insulating material (a part of the secondary electron emission layer 110) filled between the plurality of metal blocks on the layer formation surface 140 of the underlayer 130. In the present embodiment, the number of resistive layers 120 present between the channel-forming surface 101 and the secondary-electron emission surface 111 of the substrate 100 is not limited to 1. The plurality of metal blocks constituting the resistive layer 120 are preferably made of a material having positive temperature characteristics in resistance value, such as Pt, Ir, Mo, or W. The inventors have confirmed that, for example, when the resistive Layer 120 is formed of a single Pt Layer including a plurality of Pt blocks planarly formed by an Atomic Layer Deposition (ALD), the gradient of the temperature characteristic of the resistance value becomes smaller as compared with a structure in which a plurality of Pt layers are stacked with an insulating material interposed therebetween (see fig. 9). Here, the crystallinity of each metal piece was confirmed by a pattern obtained by XRD analysis. For example, in the case where the metal block is Pt, in the present embodiment, as shown in fig. 10 (a), a pattern having peaks whose full widths at half maximum are at an angle of 5 ° or less is obtained at least on the (111) plane and the (200) plane. In fig. 10 (a) and 10 (b), the (111) surface of Pt is represented by Pt (111), and the (200) surface of Pt is represented by Pt (200).

The presence of the underlayer 130 shown in fig. 2 (b) does not affect the temperature dependence of the resistance value of the entire electron multiplier. Therefore, the structure of the electron multiplier according to the present embodiment is not limited to the example shown in fig. 2 (b), and may have a cross-sectional structure as shown in fig. 2 (c). Unlike the cross-sectional structure shown in fig. 2 (b), the cross-sectional structure shown in fig. 2 (c) does not include a base layer between the substrate 100 and the secondary electron emission layer 110, and the channel formation surface 101 of the substrate 100 functions as the layer formation surface 140 on which the resistive layer 120 is formed. The other structure in fig. 2 (c) is the same as the cross-sectional structure shown in fig. 2 (b).

In the following description, the structure in which Pt is applied as a metal block constituting the resistive layer 120 and having a positive temperature characteristic in resistance value will be described.

Fig. 3 and 4 (a) to 4 (b) are diagrams for quantitatively explaining the relationship between the temperature and the electrical conductivity of the electron multiplier, particularly the resistive layer according to the present embodiment. In particular, fig. 3 is a schematic diagram for explaining an electron conduction model of a single Pt layer (resistive layer 120) formed on the layer forming surface 140 of the undercoat layer 130. Fig. 4 (a) shows an example of a cross-sectional model of an electron multiplier according to the present embodiment, and fig. 4 (b) shows an example of a cross-sectional model of an electron multiplier according to a comparative example.

In the electron conduction model shown in fig. 3, the Pt blocks 121 constituting a single Pt layer (resistive layer 120) are separated from each other by a distance L between localized regions (e.g., a part of the secondary electron emission layer 110 in contact with the layer formation surface 140 of the underlayer 130) where free electrons are not present, as delocalized regions where free electrons are present on the layer formation surface 140 of the underlayer 130_I. In the present embodiment, the average thickness S and the distance (minimum distance between Pt blocks adjacent to each other via the insulating material) L in the stacking direction of the plurality of Pt blocks 121 (metal blocks having a positive temperature characteristic in resistance value) that constitute the resistive layer 120 and are two-dimensionally arranged on the layer formation surface 140 with a part (first insulating material) of the secondary electron emission layer 110 interposed therebetween (i.e., the resistance value of the metal blocks) are_ISatisfies S>L_IThe relationship (2) of (c). As shown in fig. 3, the average thickness S of the Pt blocks is defined by the thickness of the film when a plurality of Pt blocks are flattened into a film shape (hatched portions in fig. 3). The average thickness S corresponds to the thickness of the resistive layer 120.

As shown in fig. 4 (a), the cross-sectional structure of the model assumed as the electron multiplier according to the present embodiment is configured as follows: a substrate 100; a base layer 130 provided on the channel forming surface 101 of the substrate 100; a resistive layer 120 provided on the layer forming surface 140 of the undercoat layer 130; and a secondary electron emission layer 110 having a secondary electron emission surface 111 and disposed so as to sandwich the resistive layer 120 together with the underlayer 130.

On the other hand, the cross-sectional structure of the model assumed as the electron multiplier of the comparative example is, as shown in fig. 4 (b), composed of: a substrate 100; a base layer 130 provided on the channel forming surface 101 of the substrate 100; a resistive layer 120A provided on the layer formation surface 140 of the undercoat layer 130; and a secondary electron emission layer (insulator) 110 having a secondary electron emission surface 111 and disposed so as to sandwich the resistive layer 120A together with the underlayer 130. The difference in structure between the model of the present embodiment (fig. 4 (a)) and the model of the comparative example (fig. 4 (B)) is that the resistive layer 120 of the model of the present embodiment is formed of a single Pt layer, and the resistive layer 120A of the model of the comparative example has a structure in which a plurality of Pt layers 120B are laminated from the channel forming surface 101 to the secondary electron emission surface 111 with an insulator layer interposed therebetween.

In each Pt layer formed on the substrate 100, an insulating material (e.g., MgO or Al) is filled between Pt blocks having any one of a plurality of discretely-existing levels₂O₃) Free electrons in a certain Pt bulk 121 (delocalized region) move to the Pt bulk 121 adjacent to the Pt bulk 121 via the insulating material (localized region) by tunneling (hopping). In such a two-dimensional electron conduction model, the conductivity (reciprocal of resistivity) σ for the temperature T is given by the following equation. Further, since the jump in the layer formation surface 140 in which the plurality of Pt blocks 121 are two-dimensionally arranged on the layer formation surface 140 is examined, it is considered to be limited to a two-dimensional electron conduction model.

[ mathematical formula 1 ]

σ: conductivity (1/omega)

σ₀: conductivity of ∞ T

T: temperature (K)

T₀: temperature constant

k_B: boltzmann coefficient

N(E_F): density of states

L_I: distance (m) between non-localized regions

Fig. 5 is a graph (G410, G420) of a fitting function obtained based on the above equation, and is a graph obtained by plotting actually measured values of a plurality of samples. In FIG. 5, graph G410 is represented by Al₂O₃A Pt layer having a thickness adjusted to 7 "cycles" is formed on the layer formation surface 140 of the underlying layer 130 by ALD, and Al having a thickness adjusted to 20 "cycles" is formed by ALD₂O₃The conductivity σ of the sample (secondary electron emission layer 110), and the symbol "○" are measured values thereof, wherein the unit "period" is an "ALD period" indicating the number of atomic injections by ALD, the layer thickness of the formed atomic layer can be controlled by adjusting the "ALD period"₂O₃A Pt layer having a thickness adjusted to 6 "cycles" is formed on the layer formation surface 140 of the underlying layer 130 by ALD, and Al having a thickness adjusted to 20 "cycles" is formed by ALD₂O₃It is understood from the graphs G410 and G420 of fig. 5 that, even in the configuration in which the Pt blocks 121 constituting the resistive layer 120 are arranged in a planar manner, setting the thickness of the resistive layer 120 (defined by the average thickness of the Pt blocks 121 in the stacking direction) to be thicker improves the temperature characteristics of the resistance value of the resistive layer 120.

Qualitatively, in the case of the model of the electron multiplier according to the present embodiment shown in fig. 4 (a), only a single Pt layer is formed between the channel formation surface 101 and the secondary electron emission surface 111 of the substrate 100. That is, in the present embodiment, the Pt block 121 having crystallinity of such an extent that a peak having a full width at half maximum of 5 ° or less can be observed at least in the (111) plane and the (200) plane in the pattern obtained by XRD analysis is formed on the layer formation surface 140. As described above, in the present embodiment, the conductive region is limited within the layer formation surface 140, and the number of hops of free electrons that move between the Pt blocks 121 due to the tunnel effect is small.

On the other hand, in the case of the model of the electron multiplier according to the comparative example shown in fig. 4 (B), the resistive layer 120 provided between the channel forming surface 101 and the secondary electron emission surface 111 of the substrate 100 has a laminated structure in which a plurality of Pt layers 120B are arranged with insulating layers interposed therebetween. In particular, in such a structure in which a plurality of Pt layers 120B are stacked, crystallinity of each Pt block 121 cannot be confirmed (a plurality of peaks cannot be confirmed in a pattern obtained by XRD analysis). As described above, in the comparative example of fig. 4 (b), since each Pt block is small, the crystallinity is low, the number of jumps is large, and the conductive region is expanded not only in the layer formation surface 140 but also in the lamination direction, and therefore, negative temperature characteristics are more strongly exhibited with respect to the resistance value. In contrast, in the present embodiment, the temperature characteristics of the resistance value are effectively improved due to the restriction of the conductive region and the reduction in the number of times electrons jump between the Pt blocks (metal blocks constituting a single Pt layer) formed in a planar manner.

Fig. 6 (a) is a TEM image of a cross section of the electron multiplier according to the present embodiment having the cross-sectional structure (single-layer structure) shown in fig. 4 (a), and fig. 6 (b) is an SEM image of the surface of a single Pt film (resistive layer 120). The TEM image in fig. 6 (a) is a multiband interferogram of a sample having a thickness of 440 angstroms (44 nm) set at an acceleration voltage of 300 kV. The sample of the electron multiplier according to the present embodiment for obtaining the TEM image (fig. 6 (a)) has a laminated structure in which the underlayer 130, the resistive layer 120 made of a single Pt layer, and the secondary electron emission layer 110 are provided in this order on the channel formation surface 101 of the substrate 100. On the other hand, a sample of the electron multiplier according to the present embodiment, from which an SEM image (fig. 6 (b)) was obtained, was used from which the secondary electron emission layer 110 was removed in order to observe the Pt film. The thickness of a single Pt layer (resistive layer 120) was adjusted by ALD to14[ period ]]Amount of (a) of₂O₃The thickness of the secondary electron emission layer 110 formed was adjusted to 68[ period ] by ALD]The amount of (c). The single Pt layer (resistive layer 120) has a structure in which an insulating material (a part of the secondary electron emission layer) is filled between Pt blocks 121. The layer 150 shown in the TEM image shown in fig. 6 (a) is a surface protective layer provided on the secondary electron emission surface 111 for TEM measurement.

The first insulating material constituting the secondary electron emission layer 110 and the second insulating material constituting the underlayer 130 may be different from each other or the same. Further, the position of the resistive layer provided on the channel-forming surface 101 of the substrate 100 can be set arbitrarily. For example, in the example shown in fig. 7 (a), the thickness S1 of the secondary electron emission layer 110 sandwiching the resistive layer 120 together with the underlayer 130 is larger than the thickness S2 of the underlayer 130. In this case, the resistive layer 120 is formed at a position closer to the secondary electron emission surface 111 than the channel formation surface 101. By forming the underlayer 130 thick, when a material having low film formation stability by ALD is used for the resistive layer 120, the film formation stability of the resistive layer 120 can be improved. In contrast, in the example shown in fig. 7 (b), the thickness S1 of the secondary electron emission layer 110 sandwiching the resistive layer 120 together with the underlayer 130 is smaller than the thickness S2 of the underlayer 130. In this case, the position of the resistive layer 120 is formed at a position closer to the channel formation surface 101 than the secondary electron emission surface 111. By forming the secondary electron emission layer 110 thick, the gain of the electron multiplier can be increased.

On the other hand, fig. 8 (a) is a diagram showing an example of a cross-sectional structure (corresponding to the cross-section of fig. 4 (b)) of the electron multiplier according to the comparative example, and fig. 8 (b) is a TEM image thereof. As shown in fig. 8 (a), the cross-sectional structure of the electron multiplier according to the comparative example was constituted by: a substrate 100; a base layer 130 provided on the channel forming surface 101 of the substrate 100; a resistive layer 120A provided on the layer formation surface 140 of the undercoat layer 130; and a secondary electron emission layer 110 having a secondary electron emission surface 111 and disposed so as to sandwich the resistive layer 120A together with the underlayer 130. In the model of the comparative example (fig. 8 (a)), the resistive layer 120A has a multilayer structure in which a plurality of Pt layers 120B are laminated from the channel formation surface 101 to the secondary electron emission surface 111 with an insulator layer interposed therebetween. In addition, the Pt layers 120B each have a structure in which an insulating material (a part of the secondary electron emission layer) is filled between the Pt blocks 121.

The TEM image in fig. 8 (b) is a multiband interference pattern of a sample having a thickness of 440 angstroms (44 nm) and obtained by setting the acceleration voltage to 300kV, and the resistive layer 120A is made of Al with the Al interposed therebetween₂O₃The insulating material of construction is composed of 10 layers of Pt layer 120B. The thickness of each insulating layer between the Pt layers 120B was adjusted to 20[ cycles ] by ALD]The thickness of each Pt layer 120B was adjusted to 5[ cycles ] by ALD]Of Al, further₂O₃The thickness of the secondary electron emission layer 110 formed was adjusted to 68[ period ] by ALD]The amount of (c). The layer 150 shown in the TEM image shown in fig. 8 (b) is a surface protective layer provided on the secondary electron emission surface 111 of the secondary electron emission layer 110.

Next, a comparison result between an MCP sample to which the electron multiplier according to the present embodiment is applied and an MCP sample to which the electron multiplier according to the comparative example is applied will be described with reference to fig. 9 and 10.

The sample of the present embodiment has a thickness of 220 angstroms (═ 22nm) and has a cross-sectional structure shown in fig. 4 (a). This sample had a laminated structure in which a base layer 130, a resistive layer 120 composed of a single Pt layer, and a secondary electron emission layer 110 were sequentially provided on a channel formation surface 101 of a substrate 100. The single Pt layer (resistive layer 120) has a structure in which an insulating material (a part of the secondary electron emission layer) is filled between Pt blocks 121, and the thickness thereof is adjusted to 14[ cycles ] by ALD]The amount of (c). From Al₂O₃The thickness of the secondary electron emission layer 110 formed was adjusted to 68[ period ] by ALD]The amount of (c).

On the other hand, the sample of the comparative example is a sample having a thickness of 440 angstroms (44 nm) and having a cross-sectional structure shown in fig. 4 (b). This sample had a laminated structure in which a base layer 130, a resistive layer 120A, and a secondary electron emission surface 111 were provided in this order on a channel formation surface 101 of a substrate 100. The resistive layer 120A has a structure in which 10 Pt layers 120B are stacked with an insulator interposed therebetween.In addition, the Pt layers 120B each have a structure in which an insulating material (a part of the secondary electron emission layer) is filled between the Pt blocks 121. In addition, the thickness of each insulating layer located between the Pt layers 120B was adjusted to 20[ cycles ] by ALD]The thickness of each Pt layer 120B was adjusted to 5[ cycles ] by ALD]Of Al, further₂O₃The thickness of the secondary electron emission layer 110 formed was adjusted to 68[ period ] by ALD]The amount of (c).

Fig. 9 is a graph showing the temperature characteristics (during 800V operation) of the normalized resistance of each of the sample of the present embodiment and the sample of the comparative example having the above-described structure. Specifically, in fig. 9, a graph G710 shows the temperature dependence of the resistance value of the sample of the present embodiment, and a graph G720 shows the temperature dependence of the resistance value of the sample of the comparative example. As can be seen from fig. 9, the inclination of the graph G710 is small relative to the inclination of the graph G720. That is, the resistive layer 120 is configured in a state where a single Pt layer is two-dimensionally confined on the layer formation surface, and thus the temperature dependence of the resistance value is improved. As described above, according to the present embodiment, the temperature characteristics are stable in a wider temperature range than in the comparative example. Specifically, when the electron multiplier according to the present embodiment is applied to the field of image intensifiers and the like, for example, the allowable temperature dependence is preferably in a range in which the resistance value at-60 ℃ is 2.7 times or less and the resistance value at +60 ℃ is 0.3 times or more, based on the resistance value at 20 ℃.

Fig. 10 (a) is a spectrum obtained by XRD analysis of a sample in which a film equivalent to the film formation for MCP (the model of fig. 4 (a) using a Pt layer) is formed on a glass substrate as a measurement sample equivalent to the electron multiplier according to the present embodiment, and a sample in which a film equivalent to the film formation for MCP (the model of fig. 4 (b) using a Pt layer) is formed on a glass substrate as a measurement sample equivalent to the electron multiplier according to the comparative example. On the other hand, fig. 10 (b) is a spectrum obtained by XRD analysis of the MCP sample of the present embodiment having such a structure. In particular, the measurement method shown in FIG. 10 (B) is an MCP sample in which electrodes of Ni-Cr alloy (Inconel: registered trademark "Inconel") are provided as the input side electrode 13A and the output side electrode 13B. Specifically, in fig. 10 (a), a pattern G810 shows an XRD pattern of the measurement sample of the present embodiment, and a pattern G820 shows an XRD pattern of the measurement sample of the comparative example. On the other hand, the XRD pattern of fig. 10 (b) was measured after removing the electrode of the Ni — Cr alloy of the MCP sample of the present embodiment. The measurement conditions of the maps shown in fig. 10 (a) and 10 (b) were set such that the tube voltage of the X-ray source was 45kV, the tube current was 200mA, the X-ray incident angle was 0.3 °, the X-ray irradiation interval was 0.1 °, the X-ray scanning speed was 5 °/min, and the length of the X-ray irradiation slit in the longitudinal direction was 5 mm.

In fig. 10 (a), in a spectrum G810 of a measurement sample of the present embodiment, peaks having a full width at half maximum of an angle of 5 ° or less appear on the (111) plane, (200) plane, and (220) plane, respectively. On the other hand, in the pattern G820 of the measurement sample of the comparative example, a peak appears only at the (111) plane, and the full width at half maximum of the peak is much larger than the angle of 5 ° (the peak shape is blunted). As described above, in the present embodiment, the crystallinity of each Pt block included in the Pt layer constituting the resistive layer 120 is significantly improved as compared with the comparative example.

As is apparent from the above description of the present invention, the present invention can be variously modified. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. An electron multiplier body, comprising:

a substrate having a channel-forming face;

a secondary electron emission layer having a bottom surface facing the channel formation surface and a secondary electron emission surface opposite to the bottom surface and emitting secondary electrons in response to incidence of charged particles, and composed of a first insulating material; and

a resistive layer sandwiched between the substrate and the secondary electron emission layer,

the resistance layer includes a metal layer in which a plurality of metal blocks made of a metal material having a positive temperature characteristic in resistance value are two-dimensionally arranged on a layer formation surface that is aligned with or substantially parallel to the channel formation surface in a state of being adjacent to each other with a part of the first insulating material interposed therebetween, and the resistance layer includes a metal layer in which a plurality of metal blocks made of a metal material having a positive temperature characteristic in resistance value are two-dimensionally arranged on a layer formation surface that is aligned

The number of layers of the metal layer existing between the channel-forming surface and the secondary-electron emission surface is limited to 1.

2. The electron multiplier body of claim 1, wherein:

the substrate further includes a base layer which is provided between the substrate and the secondary electron emission layer, has the layer formation surface at a position facing the bottom surface of the secondary electron emission layer, and is made of a second insulating material.

3. The electron multiplier body of claim 2, wherein:

the first insulating material and the second insulating material are different from each other.

4. The electron multiplier body of claim 2, wherein:

the second insulating material is the same insulating material as the first insulating material.

5. The electron multiplier body of claim 2, wherein:

the first insulating material is MgO and the second insulating material is Al₂O₃Or SiO₂。

6. The electron multiplier body of any one of claims 2 to 5, wherein:

the secondary electron emission layer is thicker than the base layer with respect to a thickness of each layer defined in a lamination direction from the channel formation surface to the secondary electron emission surface.

7. The electron multiplier body of any one of claims 2 to 5, wherein:

the secondary electron emission layer is thinner than the base layer with respect to a thickness of each layer defined in a lamination direction from the channel formation surface to the secondary electron emission surface.

8. The electron multiplier body of any one of claims 1 to 7, wherein:

at least 1 group of metal blocks adjacent to each other with a part of the first insulating material interposed therebetween among the plurality of metal blocks constituting the metal layer satisfies the following relationship: the minimum distance of the 1 group of metal blocks is shorter than the average thickness of the metal blocks specified in the lamination direction from the passage forming surface to the secondary electron emission surface.

9. The electron multiplier body of any one of claims 1 to 8, wherein:

the resistive layer has a temperature characteristic in the following range: a resistance value of the resistive layer at-60 ℃ of 2.7 times or less and a resistance value of the resistive layer at +60 ℃ of 0.3 times or more with respect to a temperature of 20 ℃.